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951.
Marengo Jose A. Cunha Ana Paula M. A. Nobre Carlos A. Ribeiro Neto Germano G. Magalhaes Antonio R. Torres Roger R. Sampaio Gilvan Alexandre Felipe Alves Lincoln M. Cuartas Luz A. Deusdará Karinne R. L. Álvala Regina C. S. 《Natural Hazards》2020,103(2):2589-2611
Natural Hazards - Historically, during periods of extreme drought, food security in the drylands of the semiarid region of Northeast Brazil (NEB) is under severe risk due to agricultural collapse.... 相似文献
952.
Roger M. Jacobi Peter J. Rowe Mabs A. Gilmour Rainer Grün Timothy C. Atkinson 《第四纪科学杂志》1998,13(1):29-42
Uranium-series dating of derived speleothem suggests that the sediments enclosing a Middle Palaeolithic stone artefact assemblage in Pin Hole Cave probably accumulated after about 64 ka, and 14C dates indicate a likely age of > 40 ka for the large mammal fauna associated with it. Electron spin resonance data from the fauna conform with these age constraints and are consistent with accumulation between 38 and 50 ka. This evidence supports the view that Britain was recolonised by hominids during Oxygen Isotope Stage 3. Stratigraphically higher stone tool industries demonstrate the local presence of both early Upper and late Upper Palaeolithic cultures. © 1998 John Wiley & Sons, Ltd. 相似文献
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954.
1 Introduction A series of studies have indicated that there were two extensional phases in the North Sea (Fig. 1). An earlier period (Late Permian-Early Triassic) of rifting occurred widely in these areas, with predominant extension direction of W-E (F?rseth, 1996; F?rseth et al., 1997). In contrast to the widely distributed Permo-Triassic extension, Jurassic extension in the North Sea were generally much more localized into the three main rift arms (Fig. 1): the Viking Graben, Moray… 相似文献
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The 2013 European Seismic Hazard Model: key components and results 总被引:11,自引:5,他引:6
Jochen Woessner Danciu Laurentiu Domenico Giardini Helen Crowley Fabrice Cotton Gottfried Grünthal Gianluca Valensise Ronald Arvidsson Roberto Basili Mine Betül Demircioglu Stefan Hiemer Carlo Meletti Roger W. Musson Andrea N. Rovida Karin Sesetyan Massimiliano Stucchi The SHARE Consortium 《Bulletin of Earthquake Engineering》2015,13(12):3553-3596
958.
Streams and rivers, particularly smaller ones, often do not maintain steady flow rates for long enough to reach equilibrium conditions for sediment transport and bed topography. In particular, streams in small watersheds may be subject to rapidly changing hydrographs, and relict bedforms from previous high flows can cause further disequilibrium that complicates the prediction of sediment transport rates. In order to advance the understanding of how bedforms respond to rapid changes in flow rate,... 相似文献
959.
Mt. Ruapehu, in the central North Island of New Zealand, is one of the most lahar-prone volcanoes in the world. Since historic
observations began in 1861 AD, more than 50 individual lahars have been recorded in the Whangaehu valley alone, the natural
outlet to the summit Crater Lake. These lahars have been triggered by a variety of mechanisms, including explosive eruptions
that displaced Crater Lake water over the outlet or ejected it onto the snow-clad summit area of the volcano; rain-remobilisation
of tephra deposits on steep slopes; displacement over the outlet as a result of syn-eruptive changes in lake bathymetry; and
lake break-outs from Crater Lake following impoundment of excess water behind temporary barriers of tephra and/or ice emplaced
over the outlet. However, only 9 lahar deposits can be distinguished in the upper Whangaehu valley on sedimentological, stratigraphic,
geomorphic and petrological grounds, and these are skewed towards either the largest or the most recent flows. In some cases
magnitude can be reconstructed from deposit geometry, with the largest lahars producing the highest level terraces, the coarsest
deposits, and crossing drainage divides into normally inactive channels. This under-representation of historic events reflects
the low preservation potential of unconsolidated deposits in a steep alpine environment, and the overprinting and recycling
effect of large magnitude lahars that rework material down to bedrock and effectively reset the stratigraphic record. Development
of magnitude-frequency relationships for Ruapehu lahars therefore requires the identification of lahar deposits in proximal,
medial and distal settings in order to ensure that the full range of events is represented. 相似文献
960.